Coating of articles by means of cathode disintegration



A ril 22, 1941. W. BURKHARDT ETAL 2,239,642

COATING OF ARTICLES BY MEANS OF CATHODE DISINTEGRATION Filed May 21, 1937 5 Sheets-Sheet l Ear/ Ramart April 1941- w. BURKHARDT EI'AL 2,

COATING 0F ARTICLES BY MEANS QF CATHODE DISIN'I 'EGRATION Filed Bay 21. 1937 I 5 Sheets-Sheet 2 April 22, 1941. w. BURKHARDT arm. 2,239,642

COATING 0F ARTICLES BY MEAN 0F CATHODE DISINTEGRATION Find May 21, 1937 5 Sheets-Sheet s April '22, 1941- w. BURKHARDT arm.

COATING OF ARTICLES BY MEANS OF CATHODE DI SINTEGRN IION 5 Sheets-Sheet 4 Filed Bay 21, 1937 April 22, 1941. w. BUR KHARDT El'AL 2,239,642

COATING 05 ARTICLES BY MEANS OF CATHODE DISIN'IEGRATION FilodMay 21, 1937 5 Sheets-Sheet 5 II H I hun )Qwew Hana Patented Apr. 22, 1941 COATING F ARTICLES BY MEANS OF CATHODE DISINTEGRATION Wilhelm Burkhardt, Berlin-Grunewald, and Hermann Ramert, Rudolf Reinecke, and Eilhart Wehnelt, Berlin-Lankwitz, Germany, assignors to Bernhard Berghaus, Berlin-Lankwitz, Germany Application May 21, 1937, Serial No. 144,080 In Germany May 27, 1936 19 Claims.

The present invention relates to a method and apparatus for coating articles with particles released from the material forming the cathode wherein the particles are guided onto the article to be coated.

The processes hitherto employed for coating metallic or non-metallic articles by means of cathode distintegration are uneconomical, because a great part of the material spattered from the cathode in all directions does not reach the article to be coated, but is distributed almost uniformly in space and is mostly deposited on the walls of the distintegration vessel. Only a fractional portion of the particles thrown from the cathode hits the article to be bespattered. This dispersion of the particles is particularly uneconomical in the disintegration of costly metals and has the further disadvantage, that for obtaining layers of given thickness it is necessary to continue the bespattering for long periods of time.

Through th present invention these disadvantages are overcome. The invention relates to a process for coatingmetallic or non-metallic articles by means of cathode disintegration wherein the cathode is disintegrated in a magnetic field.

ode being directed and collected, these particles are almost all utilised for the coating of the arti-.

small surfaces.

Through the magnetic control of the particles,

' for instance-through theemployment of a plu- The particles which are spattered from the oath- .the particles spattered from the cathode can be optionally varied. The directed and charged particles emanating from the cathode may also be conveyed through additional magnetic fields which are arranged transversely to the direction of the field and preferably perpendicularly to one another and the magnetic fields may be influencedin such a manner that the clustered particles sweep over a surface. In many cases it will be of advantage to move only the article to be bespattered.

The cathode may be preheated in a manner known per se, for instance by resistance or high frequency heating, in order to increase the amount disintegrated per unit of time. Through the particles emitted or spattered from the cathrality of electromagnets, every desired surface can be swept over uniformly. The process has the further advantage, that in coating heat-sensitive articles, while maintaining the greatest economy as'compared with the known processes, the distance from the heated cathode may nevertheless be greater.

According to a further feature of the invention the anode of the disintegration system may be disposed in such a manner between the cathode and the article to be coated that it is outside the stream of particles or beam which is spattered from the cathode and is charged and directed,

or collected by one or more magnetic fields. The particles spattered from the preferably additionally heated cathode, which are charged and directed or collected by one or more magnetic fields, may be conducted through an anode having an aperture on to the article to be coated. The anode provided with an aperture may with advantage be made in the form of a ring-shaped member. Through the anode being given the form of a ring, there is this advantage among others, that all the parts required for the disintegration can be arranged in one vessel, the disintegrator and that the .disinte rator with the disintegration chamber may be arranged so as to be removable or disconnectable with a flange or ground-in connection. With this arrangement the article can be coated unhindered by the anode. The ring-shaped form of the anode furthermore causes a uniform distri-. 'bution of the field. The anode is preferably so arranged as to be in the proximity of the oathode. The minimum distance to be observed is dependent on the disintegration voltage applied and on the prevailing vacuum.

The collected stream of particles may also be conducted through an additional static field, for

In certain cases the particles may be particles. The braking effect of the negatively charged cylinder may be equalised by the provision of an additional positive accelerating anode which may with advantage also be ringshaped. For coating non-metallic articles the accelerating electrode may be positioned behind the article, for instance a glass plate which is to be coated may be laid on a metal plate as the auxiliary electrode. Even when a concentration cylinder is not used, the acceleration of the particles by the employment of an accelerating electrode presents advantages. In the case of an article connected up as an accelerating electrode the particles will, owing to this expedient, impinge on the article with increased energy and the layers formed will adhere more firmly. Moreover, the particles give up their charge when striking the article which is connected as an accelerating electrode, so that any charging of the article which would detrimentally affect the coating is avoided. In the case of non-metallic articles the accelerating electrode disposed behind the article produces a capacitive retention of the charges which arrive with the particles.

In carrying out the invention the cathode may i be heated whereby the quantity of material released by the cathode for coating is increased. The heating and the" disintegration of the cathodes may preferably be carried out periodically in time intervals in such a manner that, while the disintegrating voltage is effective, the heating is discontinued and, while the heating is effective, the disintegration is discontinued. In this way unfavourable disintegration conditions which may occur, such as field disturbances by the heating currents and an increase in pressure immediately in front of the cathode, which is caused by the accumulation of disintegrated particles are avoided. The periodic disintegration and heating may further be regulated in such a manner that the heating impulses are kept short with respect to the disintegration impulses and that the disintegration impulse consists for instance of several half waves of a rectified alternating current. I

The invention also relates to apparatus for carrying out the described process, which consists substantially of a vacuum vessel with one or more cathodes and anodes disposed therein, which are fed from one or more sources of current, and

with one or more holding devices for the article or articles to be coated and one or more field coils energised by one or more sources of current for collecting the particles emitted by the cathode. Furthermore, additional magnetic fields which are preferably perpendicular to one another may be disposed transversely to the di-.

rection of motion of the particles emitted by the cathode.

The field coil for collecting the emitted particles may be water-cooled. The wire of the coil or the entire coil may be coated with an insulating layer, for instance a layer of oxide or the like, for preventing secondary discharges, when the coil is disposed within the vessel. In the case of disintegration of metals the cathode may with advantage be in, the form of a cluster of wires arranged in the direction of the field. This provides the advantage, that the particles which are spattered off mainly from the two ends of the cluster of wires are collected, so that two bodies can be metallised at the same time. The collecting effect is'with advantage assisted through the cathode being constructed as a hollow cathode. The hollow cathode may for instance be of spherical, parabolic, cylindrical or some such form. The material to be disintegrated may be spattered off from the interior of the hollow cathode. A cathode of any form may also with advantage be disposed within a hollow cylinder, so that the particles spattered of! from the cathode are preliminarily directed or preliminarily collected by the directional and collecting effect of the field of the hollow cylinder which is at the same potential. The cathode may be preheated in this case as well.

The invention also relates to apparatus for carrying out the described process, which is characterised by a disintegrator consisting of a vacuum vessel with a cathode disposed therein and fed from a heating current source and with an anode provided with an opening, for instance a ring-shaped anode, and fed from a disintegration current source, and with one or more field coils energised by a source of current for collecting the particles spattered of! from the cathode. with an additional controlling device 'for the collected stream of particles, and by a chamber which is in communication with the disintegrator which is removable and disconnectable by means of a flange or a ground-in connection and in which chamber the article to be coated is disposed. The apparatus is further characterised by an additional concentrating cylinder and by an accelerating electrode. The apparatus is further characterised by a plurality of disintegrators provided with an air inlet cock on a chamber which is capable of being evacuated, which are for instance so arranged as to be capable of being exchanged during operation each by means of a ground-in connection and a sliding shutter. The apparatus is further characterised by the feature, that the bespattering chamber is provided with closable chambers for enclosing the article to be coated, which are in communication with an air inlet cock and a vacuum pump.

Various devices for carrying out the method are illustrated diagrammatically by way of example in the accompanying drawings, in which ,Fig. 1 is a vertical section through cathode disintegration apparatus,

Fig. 2 is a similar sectional view showing a different form of cathode and field,

Fig. 3 is a sectional view. of an arrangement with additional control for sweeping over surfaces and Figs. 4, 5 and 6 are sectional views of special constructional forms of the cathode.

Fig. 7 is a section through another complete apparatus for cathode disintegration,

Fig. 8 is a sectional view of a part of a cathode disintegration apparatus with a concentrating cylinder,

Fig. 9 is a section through a resistance-heated cathode.

Fig. 10 is a section through a high frequencyheated cathode,

Fig. 11 is a section through an arc-heated cathode,

Fig. 12 is a section through disintegration apparatus according to a second constructional example,

Fig. 13 is a section through a portion of a disintegration apparatus according to a third constructional example with closable chambers for the article to be treated in the bespattering chamber.

In Fig. 1 which is a vertical section through cathode disintegrating apparatus, l is a vacuum vessel composed of a bottom part 2 and a bell 3, which are connected together in an airtight manner. The vacuum vessel may be made of. glass, porcelain, metal or the like. sents a connecting branch leading to the vacuum pump. The disintegration vessel can be filled with gases through the connecting branch 4b, for instance with hydrogen or with gases which do not affect the metal to be disintegrated, such as argon, neon, helium or the like, or with gases which react chemically with the metal to be disintegrated. Gases may also be used, which for instance improve the effect, such as hydrocarbons, silicon hydride or other similar gases. The gas pressure in the disintegration vessel and the disintegration voltage depend entirely on the kind of cathode to be disintegrated and on its geometrical dimensions. The gas pressure may in general vary within the limits, within which the conduction of electricity is at all possible and may thus amount to for instance from 0.01 to 1 millimeter of mercury. A lead for the cathode 6 is sealed in the wall of the vessel by means of a fitting 5 and the cathode is.covered with a non-conductor, for instance a glass plate I, in order to prevent undesired disintegration at its rear end. The cathode may be of any shape and may consist for instance of a plate or a rod, a wire or-of one or more clusters of wires, which are made of the metal to be disintegrated. In many cases it may be of advantage to employ additional heating for the cathode, more particularly when it is not sufliciently heated by the glow current, an expedient which is also to be recommended in the case of metals having a high melting point. -8 represents a fitting whichis secured for instance by springs and through which the anode 9 is led in. The fitting 8 is provided with a supporting frame I with an adjustable supporting member II, on

0a repre- 1 'lected, that is on the required flux. In an experiment, in which copper was to be disintegrated, a' current strength of- 26 amperes at a voltage of 30 volts was used for the excitation of the magnet coil l5 which had an internal diameter of about centimeters and a width of about 10 centimeters and which with 300 turns gave a field of about 225 gauss. The particles were collected on an area of 4 square centimeters which particles would otherwise, without the employment of the magnetic field, have distributed themselves almost uniformly in the disintegration vessel. The result of using this magnetic field was, that the loss which occurs in cathode disintegration without the use of a magnetic field was to a great extent .eliminated. The current source for the disintegration supplied a voltage of for instance 1800 to 2000 volts and the current strength was for instance about 10 to 12 milliamperes. Without the action of a magnetic field 4.4 milligrams were spattered on a plate having a superficial area'of 80 square centimeters and the entire surface was covered. When a magnetic field was employed, 10.4 milligrams were spattered on and only the twentieth part of the plate was covered, The thickness of the layer had thus increased 46 times. This is of special importance, when costly metals are being used as the metal to be spattered on. The cathode may consist of metals of all kinds, of alloys or of non-metals.

Fig. 2 shows a cathode of special construction and a different position of the field. In this case the cathode consists of a cluster of wires 24, held together on the supporting lead 25. The magnet coil 26 for collecting the particles emitted by I the cathode is in this case disposed for instance which rests the article l2 to be coated, 'for inare directed and collected by a magnetic field produced by a coil I5 which is arranged around the vacuum vessel. The coil l5 may be disposed either outside or inside the vessel and may if necessary be movably supported, so as to enable its position with respect to the cathode to be altered in any desired way, whereby. a change in the direction of the spattered-oil particles is effected. The coil consists, for instance, of a hollow copper tube adapted to be connected at one end- I! with a water supply pipe and at the other end I8 with a water discharge pipe,'in or-' der to conduct away the heat due to .electric losses. The material of the coil, when the latter is disposed within the disintegration vessel, may with advantage be coated with a lessconductive layer or an insulating layer, for instance an oxide layer. [9 is a source of current which is connected to the ends I! and I8 of .thecoil l5 by means of shackles I6 through a regulating resistance. The circuit to the coil l5 includes an ammeter 20 and a vo--neter 2|.

The cathode 6 and the anode 9 are connected with a source of current 22 througlr-a regulable resistance 23. The strength of .the voltage to be used is entirely governed by the kind of electrodes employed, the way they are arranged-and their geometrical dimensions and on the strength of the glow current, also on the vacuum. The current which is sent from the source of current l9 by way of a regulating resistance through the magnet coil l5 depends on the degree to which the disintegrated metal particles are to be colinside the vacuum vessel I. The current supply to the magnetic field is the same as that shown in Fig. 1. In this arrangement the oathode is disintegrated in two directions, so that there is the advantage that two articles 21 and 28, which are removably suspended from fittings 29 and 30, can be simultaneously treated. I3 represents the spattered-on metallic layer. 9 are the anodes .which may also be arranged at other points of the vessel.

In Fig. 3 is shown an arrangement for the ad-- ditional control of the metal particles 32 already collected by the coil 3|, which enables an article of larger superficial area to be swept over, the metal particles being controlled in the desired sense, for instance by changing the fields produced by electromagnets33 and 3 3 which are disposed preferably perpendicularly to one another transversely to the direction of travel of the particles.

The magnets may also be disposed externally of the vessel, for simplifying the construction. 6 is again the cathode and 9 the anode and I0 is the supporting framework for the article l2 resting on the support I I. By varying the magnetic fields 33 and 30 the stream of metal particles can be causedto play in any desired manner over the article l2. l3 represents the spattered-on layer of metal.

The stream of metal particles can of course be additionally controlled as regards its direction, by making the field coil 3| movable or capable of pivoting.

.In Fig. 4 a special constructional form of the cathode as a hollow cathode 35 is shown. Fig. 5

shows the hollow cathode 36 in the form of a assist in a further collecting of the disintegrated that they particles. In Figure 7 there is fixed in aremovable and gas-tight manner to the preferably cylindrical disintegration vessel 38 consisting for instance of glass or quartz by means of a. flange 99 the bespattering chamber 4| containing the article 48 to be bespattered, in which chamber the article is arranged for instance on a metal plate 43 which rests on insulators 42. In the bottom of the bespattering chamber is a current lead-in 44, through which the metal plate 43 can be connected to a source of voltage. The metal plate 49 may for instance be charged positively and will then constitute the accelerating electrode. For rendering the article which is tobe bespattered easily removable, the bespattering chamber is provided with a laterally closable opening 45. By means of a plug 45 the cathode 41 is led-in to the disintegration vessel so as to be removable. At its lower end the cathode supports for instance the material 48 to be disintegrated, which may be of any form and may for instance be constructed as a cluster of wires. 49 is the anode, for instance of annular shape, which can be displaced as regards its position with respect to the cathode and through which the stream of particles thrown off by the cathode and collected by the field of a collecting coil 58 passes and produces on the article 48 to be bespattered a layer 52. The collecting coil 58 which provides the field for collecting the particles spattered ofi from the cathode is connected for instance to a continuous current source 53 through a regulable resistance 54. The current for the disintegration of the material to be disintegrated is supplied by a high tension source 55 which is connected through a regulable resistance 55 to the cathode 41 and the other pole of which is connected by way of the lead-in 51 to the anode 49 which is for instance ringshaped and adjustable in a guide 58 as regards its distance from the cathode. The source oi! high tension 55 may supply a continuous current, a pulsating or intermittent continuous current ora rectified alternating current of variable frequency. 59 and 58 are electromagnets provided with coils for controlling the stream of particles, the fields of which magnets are preferably at right angles to one another. By means of the electromagnets 59 and 58 the stream of particles can be guided to and fro and upwards and downwards over the surface of the article 48. BI is a branch for the supply of a gas. 82 is a branch leading to the vacuum pump. I

Fig. 8 shows a portion of cathode disintegration apparatus according to Fig. '7 with an additional concentrating cylinder 84 which is adjustable in a guide 53. The cylinder 84 is charged for instance negatively by way of a conductor 55 and keeps the stream of particles 5| together. The conductor 55 is sealed in the wall of the vessel "by means of a fitting 55. For the rest the parts shown are the same as in Fig. 7.

Fig. 9 shows diagrammatically a section through an additional resistance-heated cathode, the resistance-heated cathode 61 being for instance a wire which is heated by a'source of current 58 through a regulable resistance 59. 49 is the ring anode in the disintegration vessel 38. 58 is the field coil.

Fig. shows diagrammatically a section through a high frequency-heated solid cathode 18 which is heated by means of the high-frequency coil II. The high frequency coil which is screened or uncoupled with respect to the collecting field coil 58 is fed by the high frequency source 12 and is disposed outside the disintegration vessel 38. 49 is the ring anode. The screened collecting field coil 58 may be screened for instance by a hood of non-magnetic material, such as aluminium or copper, from the high frequency coil. The high frequency coil may also be constructed as a collecting coil. The magnetic coil may be disconnected during the action of the high frequency.

Fig. 11 shows diagrammatically a section through an arc-heated cathode, the cathode consisting for instance of the two electrodes. 13 and 14 which are fed from a source 18 of continuous or alternating current through a regulable resistance IT to provide an are 15. The high frequency source 55 supplies the disintegration voltage, the negative pole of which is connected through a regulable resistance 58 to a potentiometer I8 lying between the two are electrodes and the positive pole of which is connected to the ring-shaped anode 49. The are between the electrodes is struck in a known manner, for instance by short-circuiting the electrodes with one another, and the distance of the electrodes from one another is regulated in a known manner by hand or electrically or magnetically. 49 is the anode and 58 the collecting field coil.

Fig. 12 shows a section through an apparatus according to av second constructional example, the arrangement being such that a plurality of disintegrators, for instance three disintegrators I9, 88 and 8|, can during operation be connected to and disconnected from a chamber 82 which is capable of being evacuated and is provided with a charging door. The disintegrating chambers are connected at 89, 84 and 85 to extensions of the housing 82 and the lower ends of the disintegrators are provided with vacuum-tight closing slides 88, 81 and 88. The closing slide 88 is for instance shown in the closed position, so that the disintegrator 8| can be detached during the operation for the purpose of replacing the cathode to be disintegrated. 89 and 98 are the collected streams of particles, which impinge for instance on a band 9| which runs over two rollers 92 and 89. The stream 88 is shown in a deflected position. 94 is a connecting branch leading to the vacuum pump and 95 is a gas supply branch. 95, 91, and 98 are the air inlet cocks to the disintegrator. For the rest the various parts of the disintegrator are the same as in Figure 7.

Fig. 13 shows diagrammatically a section through a portion of disintegrating apparatus according to another constructional example with two closable chambers 99 and I88 for the introduction of the articles to be bespattered into the bespattering chamber |8|. I82 and |8I are the disintegrators which are connected to the chamber Ill. I84 and |85 are air inlet cocks. I88 and I8! are two closing slides which enable the disintegrators to be shut oil from the bespattering chamber. The slide I88 is closed and the slide |8'I open. The inner closing slide N8 of the closable chamber 98 is open, so that a bespattering of the article 89 by the stream of particles 8 will takeplace. The outer door I of the closable chamber 99 is closed. The closable connection 2 .leads from the closable chamber to a vacuum pump for evacuating the closable chamber 99. The closable .connection 3 serves for the admission of air to the closable chamber. The inner closing slide 4 of the closable chamber |88 is closed, so that the article 5 can be exchanged through the opened outer door 5 of the closable chamber.

a connection leading to a. vacuum pump for evacuating the closable chamber I00. The closable connection H8 serves for the admission of air into the closable chamber I00, when the latter is to be opened. nection to the bespattering chamber and I2!) a connection leading to the main vacuum pump.

The provision of closable chambers on the bespattering chamber has the advantage, that the articles to be treated canbe introduced and removed without the pressure in the bespattering chamber being varied in a manner which would interrupt the operation.

When articles are to be coated with different materials, the individual disintegrators are charged with the particular cathode materials required and the article is bespattered in succession or simultaneously with these materials.

In this way layers or mixtures, for instance alloys, may be applied. When alloys are being spattered on, the disintegrators may be arranged at an angle to one another and to the article. The article may also be so arranged as to be capable of being moved from one disintegrator to another. It is also possible to apply different layers for instance on bands simultaneously next to one another. With the apparatus it is possible to bespatter or metallise ,articles of any kind, for instance articles of metal, wool, vegetable fibres, wood, wax, cellulose, mica, porcelain, glass and so on. The treating chamber may be adapted to the shape of the articles. These examples will show the great variety of ways in which the described bespatteringapparatus can be-used.

What we claim is:

1. Apparatus for coating articles with particles obtained by cathode disintegration in a magnetic field comprising in combination, a bespattering chamber capable of being evacuated, a plurality of disintegrating chambers connected to the bespattering chamber and each having an air inlet cock, means for opening and closing the communication between the bespattering chamber and the said disintegrating chamber independently of one another, each disintegrating chamber comprising a cathode and an anode between which a cathode disintegration field is formed, and a field coil around each disintegrating chamber in order to produce a magnetic field coaxial with each one of the said cathode disintegrating fields.

2. Apparatus as claimed in claim 1, in which the bespatterlng chamber has a plurality of closable chambers arranged opposite the disintegrating chambers respectively, for enclosing the ar ticles to be bespattered, each of the said closable chambers having an air inlet cock and a communication with a vacuum pump. l

3. A method of coating articles by cathode dis- H9 is a gas supply conelectrons from the cathode towards the anode and disintegrate particles from the cathode, electrically charging the particles disintegrated from the cathode, and magnetically collecting and guiding the charged particles onto the article to be coated.

5. A method of coating articles by cathode disintegration wherein the article to be coated is arranged in a closed vessel having a cathode and an anode therein which comprises, impressing a voltage across the cathode and anode to move electrons from the cathode towards the anode and release particles from the cathode,

moving the electrons into engagement with said particles so as to impart electrical charges thereto, and magnetically collecting and directing the charged particles onto the article to be coated.

6. A method of coating articles by cathode disintegration wherein the article to be coated is arranged in a closed vessel having a cathode and an anode therein which comprises, impressing a voltage across the cathode and anode to move electrons from the cathode towards the anode and release particles from the cathode, magnetically moving the electrons into engagement with said particles so as to impart operative electrical charges thereto, and magnetically collecting .and

directing the charged particles onto the article- I to be coated.

7. A method of coating articles by cathode disintegration wherein the article to be coated is arranged in a closed vessel having a cathode and flecting said electrons to increase the path of integration wherein the article to be coated is arranged in a closed vessel having a cathode and an anode therein which comprises, impressing a voltage across the anode and the cathode to move electrons from the cathode towards the anode and disintegrate particles from the oathode, electrically charging the' particles disintemovement thereof so as to increase the collision of the electrons with said particles to impart operative electric charges thereto, and magnetically collectin and guiding. the charged particles onto the article to be coated.

8. A method of coating articles by cathode disintegration wherein the article to be coated is arranged in a closed vessel between an anode and a cathode which comprises, impressing a voltage across the anode and the cathode to move electrons from the cathode towards the anode and disintegrate particles from the cathode, producing a magnetic, field around the cathode to electrically charge and collect the particles forclustered movement onto the article to be coated.

9. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and an,

anode within said vessel, means for supporting an article to be coated within the closed vessel, a

current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, magnetic means adjacent the cathode for electrically charging said particles and said magnetic means being arranged to collect and move the charged particles in the collected state onto the article to be coated.

11. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and an anode within .said vessel, means for supporting an article to be coated within the closed vessel, a current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathole, a coil arranged axially with respect to the cathode and the anode, and an electrical source supplying current to said coil so as to produce a magnetic field for collecting and guiding said particles onto the article to be coated.

12. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and an anode within said vessel, means for supporting an article to be coated within the closed vessel, 9. current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, a coil surrounding the cathode, and an electrical source supplying current to said coil so as to produce a magnetic field for collecting and guiding the collected particles onto the article to be coated.

13. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and an anode within said vessel, means for supporting an article to be coated within the closed vessel, 2. current source for impressing a voltage across said anode and. said cathode to disintegrate particles from the cathode, magnetic means for electrically charging and collecting said particles, and additional magnetic means for guiding said collected particles onto the article to be coated.

14. Apparatus for-coating articles comprising in combination, a closed vessel, a cathode and an anode within said vessel, means for supporting an article to be coated within the closed vessel, a current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, magnetic means for electrically charging and collecting said particles, and means providing two magnetic fields for deflecting said particles onto the article to b coated.

15. Apparatus for coating articles comprising in combination a closed vessel, a cathode and a ring-shaped anode within said vessel, means for supporting an article to be coated within the closed vessel, a current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, magnetic means surrounding said cathode for electrically charging and collecting said particles so as to direct the particles through the ring-shaped anode, and a statically charged cylinder for further guiding and moving said particles onto the article to be coated.

16. Apparatus for coating articles comprising in combination, a closed vessel, acathode and an anode within said vessel, means for supporting an article to be coated within said vessel, a current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, inductive means adjacent the cathode for collecting the particles released from the cathod and directing the particles towards the article to be coated, and an accelerating electrode arranged adjacent the article to be coated.

17. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and a ring-shaped anode within said vessel, means for supporting an article to be coated within said vessel, a current source for impressing a voltage across said anode and said cathode to dis- 7 integrate particles from the cathode, inductive means adjacent said cathode for collecting said particles and directing the particles through the ring-shaped anode, a statically charged cylinder for further guiding and moving said particles onto the article to be coated, and means for adjusting the position of said anode with respect to said cathode.

18. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and a ring-shaped anode within said vessel, means for supporting an article to be coated within the closed vessel, 2. current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, magnetic means adjacent said cathode for collecting said particles and directing the particles through the ring-shaped anode, and a statically charged cylinder arranged intermediate the anode and the article to be coated for further guiding and moving said particles onto the article to be coated.

19. Apparatus for coating articles comprising in combination, a closed vessel, a cathode and an anode within said vessel, means for supporting an article to be coated within said closed vessel, means arranged outside the vessel for heating said cathode, a current source for impressing a voltage across said anode and said cathode to disintegrate particles from the cathode, magnetic means arranged outside the closed vessel and operably associated with the particles distintegrated from the cathode for electrically charging said particles and directing the charged particles onto the article to be coated.

WILHELM BURKHARDT. HERMANN RAMERT. RUDOLF REINECKE. EILHART WEHNELT. 

